1. Field of the Invention
The invention relates generally to compositions and methods for forming coatings of selected color on a substrate and more particularly varying the components in aqueous suspensions of organometallic compositions and depositing the suspensions onto a glass substrate to pyrolytically produce a stable coating film-of selected color or colors on the glass substrate.
2. Description of the Currently Available Technology
In various industrial applications, it is desirable to form a coating on glass surfaces. For example, automotive windshields have coated areas known as “shade bands” or “fade zones”. In many passenger vans, the backseat and rear windows are coated with a uniformly thick coating. These coated areas reduce visible, infrared or ultraviolet light transmittance to reduce glare, the visibility of the contents of the vehicle and/or decrease solar energy transmittance to reduce heat gain in the interior of the vehicle.
One method for forming coatings on a glass substrate is by the pyrolytic deposition of metal oxide films. In U.S. Pat. No. 3,660,061 to Donley et al., the disclosure of which is herein incorporated by reference, organometallic salts, such as acetylacetonates, are dissolved in an organic solution and are sprayed onto a hot glass surface to form a metal oxide film. In U.S. Pat. No. 4,719,127 to Greenberg, the disclosure of which is incorporated by reference, aqueous suspensions of organometallic salts are sprayed onto a hot glass surface to pyrolytically form metal oxide coatings on the surface.
The presently available coating technology is used to form gray or dark gray coatings, particularly in the automotive industry, so that the coated glass can be used with the widest number of automobile body colors without “clashing” with the automobile body color. Additionally, many of the known coated substrates change color or shade upon subsequent heating during tempering and shaping of the coated substrate. This heat induced color shift makes it difficult to produce coated materials of consistent color stability. Further, many of the known coated substrates are not chemically durable e.g. when contacted with solutions having citric acid.
As can be appreciated, it would be advantageous to provide compositions and methods for applying coating(s) of selected transmitted color onto the surface of a substrate which reduce or eliminate the limitations associated with presently known compositions and methods.